alu difficulties, nx and ny not functioning - no eval

[pwolf]

im having trouble with my alu, msot of it works but nx and ny dont seem to e working and produce the wrong outputs, also when i change the value of nx or ny in the hardware simulator it doesn't allow me to eval, i first have to change another value to get the eval button. Why is that?


 Edited to remove hdl

[cadet1620]

pwolf wrote

   Mux16(a = x1, b = notx, out = nx1);  // outs not x1 if nx is set
   Mux16(a = y1, b = noty, out = ny1);  // outs not y1 if ny is set

These Mux16s have nothing connected to their "sel" inputs.
Since nothing is connected to "nx" or "ny" I suspect that the simulator knows that nothing in the circuit changes when you changed them, hence EVAL was not enabled.

Please edit your post to remove working HDL after you get your problem solved.

--Mark

[pwolf]

cant believe the mistakes i make... thanks for the help! i shall delete the post immediately!  
Now I just need to work out the zr and ng bits, have a few ideas i think..

[cadet1620]

Read Appendix A.5.3 carefully. Very useful information in there that makes the status bits much easier.
Also see this post for a test that separates testing the computation part of the ALU from testing the status bits. It's easier to write the status bits after the rest of the ALU's working.

--Mark

[pwolf]

THank you!  Readingthe appendix helped, got stuck with trying to use the internal pin for hte subbus, and not being able to see the full error message stressed me, but after a while i got it working! I havve been at this for a good few hours today and finally have my working ALU!  If i post it here can you tell me some hints about efficiency? would be appreciated.

edited

[ybakos]

Can you please stop posting your completed implementations here on the forum?

[pwolf]

yes of course, sorry for being inconsiderate.